Glycemic index and physical exercise

Abstract

The glycemic index (GI) was originally conceived to classify carbohydrate-rich foods according to the physiological impact on post-prandial glycemia. Its utility in dietary treatment of diabetes rapidly extended to other areas of clinical nutrition, public health and sports nutrition. Due to the importance of carbohydrates (CHO) in the physiology of exercise and priority consumption of foods based on this nutrient, the concept of GI may be used in sports nutrition with an acceptable grade of effectiveness. In recent years, a growing number of investigators have shown how GI may modulate the physiological response and performance of a physical exercise. However, the great methodological variability of the available studies hinders the obtaining of a clear consensus on the selection of CHO using GI. Thus, this review focuses on the effects that the glycemic response (GR) has on the different phases that are physiologically sensitive to CHO, on the practice of physical exercise. Just as GI may help the population to make a "healthy selection" of foods, in sports nutrition, the selection of CHO having high and low glycemic index (HGI and LGI, respectively) could favor the sports performance and/or objectives of health of physical exercise. The current evidence on GI of CHO in physical exercise and the need for future studies, with a standardized research methodology, are discussed in the present review.